1. Field of the Invention
This invention relates to oil pumps, and more particularly to tubing mounted oil well pumps which are activated by pumping units and cooperating sucker rod strings designed to pump oil from pools or reservoirs beneath the earth's surface. The pumps are typically fitted to tubing set in the fluid reservoir of a drilled oil well, and are activated by a string of sucker rods driven in reciprocating fashion by a surface-located pumping unit. The reciprocating action of the sucker rods causes travelling valves located within the working barrel of the pump and carried by a plunger rod in cooperation with the sucker rods, to pump the well fluid from the reserfoir to the surface.
2. Description of the Prior Art
Oil field pumps of the travelling and check valve design have been long known in the art. Typical of such pumps is the well known ball check travelling valve oil well pump, which is characterized by a working barrel, and a plunger and cooperating travelling valve in cooperation with the sucker rod string and driving unit where upward strokes of the sucker rod string and plunger rod cause fluid to flow from the reservoir in which the pump is submerged, through the bottom of the working barrle against an unseated ball check, and into a lower chamber of the pump, thus filling the chamber with fluid. Subsequent downward strokes of the sucker rod string and plunger rod effect a displacement of the upper ball check from its seat in the travelling valve, due to movement of the fluid from the lower chamber into the upper chamber, and the fluid moves on through a port in the wall of the working barrel into the tubing annulus on its way to the surface.
One of the problems associated with pumps of this design has been fluid "lock"m, a phenomenon which necessitates pulling of the pump through the tubing to the surface and correcting the problem, sometimes at great expense. Fluid or gas "lock" frequently occurs when gas is trapped in the pump and acts as a shock absorber which effectively prevents the pump from lifting fluid. Both this condition and the fluid "pound" problem, which are well known to those skilled in the art, are responsible for expense in the oil field.
Accordingly, it is an object of this invention to provide a new and improved sliding valve pump for oil wells which eliminates the necessity for the use of balls and checks in the pumping operation, and which provides a flow of fluid from the reservoir through aligned ports in the wall of the working barrel by operation of a pair of travelling valves.
Another object of the invention is to provide a new and improved oil field pump for use with pumping units and cooperating sucker rod strings which eliminates the problem of fluid and gas "lock" by operation of a pair of travelling valves which permit venting of the gas causing the lock through the wall of the pump.
Yet another object of the invention is to provide a new and improved tubing-mounted travelling valve pump for oil wells which is suspended from the tubing and extends into the oil reservoir below the tubing and is designed to receive well fluid from registering ports in the working barrel and the bottom travelling valve to permit venting of pressure in the working barrel and eliminate gas "lock".
Another object of the invention is to provide a sucker rod-activated oil well pump which utilizes a plunger to seal the bottom of the working barrel and receives fluid through a system of ports in the working barrel walls with the achievement of maximum flow and efficiency and minimum turbulence.
Still another object of the invention is to provide a new and improved oil field pump of the travelling valve design which receives reservoir fluid through registering ports in the valves and working barrel, and is designed to eliminate the necessity for fluid intake through the bottom of the working barrel.
Yet another object of the invention is to provide a new and improved tubing mounted fluid reservoir pump which is characterized by a working barrel and a pair of travelling valves slidably positioned in the barrel, with fluid entry and exit achieved by registration of ports provided in the valves and the working barrel.
A still further object of the invention is to provide a travelling valve oil pump with side ports, which is capable of effectively pumping a fluid mixture of liquid and gas without gas "lock".